Drilling fluid

ABSTRACT

An aqueous drilling fluid dispersant and a method of drilling wells using said drilling fluid which contains a substituted dihydroxybenzene compound as the dispersant, namely, a substituted dihydroxybenzene compound selected from the group consisting of 2,5-dihydroxy-1,4-benzoquinone, 2,5-dihydroxy-3,6dichloro-1,4-benzoquinone, 4,5-dihydroxy-1,2-benzoquinone, 4,5dihydroxy-3,6-dichloro-1,2-benzoquinone and mixtures of said compounds.

United States Patent Jan. 25, 1972 Kolaian I54] DRILLING FLUID [72]inventor: Jack H. Kolaian, Wappingers Falls, NY.

[73] Assignee: Texaco Inc., New York, NY.

[22] Filed: Apr. 27, 1970 [21] Appl. No.: $2,355

Related U.S. Application Data [62] Division of Ser. No. 633,434, Apr.25, I967.

[52] US. Cl. ..252/8.5 C, 252/351 [5!] Int. Cl. Cl0m 3/14,Cl0m 3/24 [58]Field ofSearch 25218.5 C, 35], 356

[56] Reierences Cited UNITED STATES PATENTS 1,999,766 4/[935 Lawton etal. ..252/8.5 2,333,l33 li/l943 Wayne ...252/8.5 2,393,273 H1946 Waynev252/85 OTHER PUBLICATIONS Rogers, Composition and Properties of OilWell Drill Fluids. second edition, Pub. 1953 by Gulf Pub. Co. ofHouston. Texas, pages 3l0 and 3l9 to 322,

Tishchenko et al., Organic Viscosity Depressants for Drilling Fluids,article in Journal of Applied Chemistry of the U.S S.R., Vol. 35, No.3,March 1962, Pages 61] to M9.

Primary Examiner-Herbert B. Guynn AtlorneyThomas H. Whaley, Carl G, Rcisand James F. Young [57] ABSTRACT An aqueous drilling fluid dispersantand a method of drilling wells using said drilling fluid which containsa substituted dihydroxybenzene compound as the dispersant, namely, asubstituted dihydroxybenzene compound selected from the group consistingof 2,5-dihydroxyl ,4-benzoquinone, 2,5-dihydroxy- 3 ,6-dichloro- I,4-benzoquinone, 4,5dihydr0xy-1,2-benzoquinone,4,5-dihydroxy-3,6-dichloro-i,Z-benzoquinone and mixtures of saidcompounds,

14 Claims, No Drawings DRILLING FLUID This is a division application ofmy application Ser. No. 633,434, filed Apr. 25, I967.

This invention relates to a novel aqueous drilling fluid for drillingwells through subsurface formations by means of welldrilling tools, andparticularly to such an aqueous well-drilling fluid having improveddispersibility as a result of containing therein a novel dispersant ashereinafter more fully described. The invention is also concerned with amethod of drilling wells employing the novel aqueous drilling fluid.

Drilling fluids, or muds as they are sometimes called, are slurries ofclayey solids used in the drilling of wells for tapping undergroundcollections of oil, gas, brine, or water. Such fluids have a number ofdifferent functions, the most important of which are to assist in theremoval of cuttings from the well, to seal off formations of gas, oil,or water which may be encountered at different levels, to lubricate thedrilling tool and drill pipe which carries the tool, and to hold thecuttings in suspension in event of shutdowns in drilling.

An ideal drilling fluid is a thixotropic colloidal system, i.e., a fluidwhich on agitation or circulation (as by pumping or otherwise), has ameasurable relatively low viscosity and is free flowing (not plastic),particularly at high temperatures; but when such agitation orcirculation is halted, the fluid sets or gels. The rate of gel formationis such as to permit the cuttings to fall only a short distance beforethe gel structure is sufficiently strong to support them.

When such a drilling fluid having the proper viscosity, the proper gelrate and proper gel strength is circulated through a well bore, it has asufficiently high viscosity to carry the cuttings and sand from thebottom of the hole to the surface and it has a gel rate such as to allowthe cuttings and sand to settle in a settling pit. On standing in aquiescent state, it develops sufficient gel strength to prevent thesettling of the cuttings, sand or weighting material, etc., in the wellbore when it becomes necessary to discontinue circulation for anyappreciable period of time. Such a fluid is also characterized by itsability to form a mud cake on the borehole wall, thereby assisting insealing off the traversed formations and inhibiting so-called waterloss, i.e., loss of water from the drilling fluid.

One of the principal problems in mud chemistry is the production ofsuitable drilling fluids having satisfactory dispersibility, and thenecessary thixotropic properties discussed above.

In accordance with the present invention the problems of dispersibilityin aqueous drilling fluids can be solved by incorporating in an aqueousdrilling fluid as the dispersant a substituted dihydroxybenzene compoundselected from the group consisting of (a) a compound having the generalformula wherein A is an alkyl, nitro, halo, hydroxy, formyl, carboxy ora carboxyalkenyl radical, B is hydrogen or halo, including mixtures ofsaid compounds, and (b) a compound having the general formula wherein Aand B both are quinoid oxygen, C and D both are hydrogen or halo, andthe quinoid tautomers thereof; said dihydroxybenzene being present inthe drilling fluid in an amount sufl'lcient to reduce the viscositythereof.

it is known from the article appearing in Zhur. Priklad. Khem. 35, pages638-647 I962), "Organic Viscosity Reducer in Clay Solutions" by D.Tischenko and S. Fleisher (CA, 57, 249lg, 1962). that theortho-dihydroxybenzenesulfonic acids, theortho-dihydroxy-alpha-toluenesulfonic acids and water soluble saltsthereof are viscosity reducing agents in clay laden drilling fluidswhereas the corresponding metaand para-dihydroxybenaenes including thecorresponding sulfonic acid derivatives and water soluble salts thereofare ineffective viscosity reducing agents for aqueous drilling fluids.

The term "substituted dihydroxybenzene compound as used in thespecification and claims is intended to cover any substituteddihydroxybenzene compound meeting either of the above general formulasincluding mixtures of such compounds.

More particularly representative substituted dihydroxybenzene compoundsof the present invention include the alkyl substituted dihydroxybenzenessuch as 4-methyl-, 4- ethyl 4-isopropyl-, 4-tertiarybutyl-, 4-hexyland4-octyl-l,2- dihydroxybenzenes, substituted dihydroxybenzenes such as 4-nitro-, 4-chloro-, 4-hydroxy-, 4-formyl-, 4-carboxy-,4-(2'-carboxyethenyl)-, and 4-methyl-5-chlorol ,Z-dihydroxybenzene,2,5-dihydroxyl ,4-benzoquinone, 2,5-dihydroxy-3,6-dichloro-1,4-benzoquinone, including the quinoid tautomers thereof,4,5-dihydroxy-l,2-benzoquinone and 4,5-dihydroxy-3,6- dichloro-l,Z-benzoquinone, respectively, and mixtures of these compounds.

it is surprising that these compounds are effective dispersants whenother related benzenes such as the ortho-, metaandpara-dihydroxybenaenes, l,2,3-trihydroxybenzene, 4- hydroxycinnamicacid, tetrahydroxy-l,4-benzoquinone, Dipotassium rhodizonate and2,3,4-trihydroxy-l-decanoylbenzene are ineffective drilling fluiddispersants.

The preferred dispersants of the present invention include the4-methyl-l,Z-dihydroxybenzene, 4-(2-carboxyethenyl)- l,Z-dihydroxybenzene, 4-carboxyl ,Z-dihydroxybenzene, 4- hydroxy-l,Z-dihydroxybenzene, 4-nitrol ,Z-dihydroxybenzene,4chloro-l,Z-dihydroxybenzene and the 4-methyl-S-chloro-l,Z-dihydroxybenzene species since these materials exhibit themost effective dispersing properties in aqueous drilling fluids.

All of the above-named preferred 1,2-dihydroxybenzene species exhibitsuperior dispersing activity and high-tempera ture stability in aqueousdrilling fluids particularly at the high bottom hole temperatureencountered in present day drilling operations. By the term high bottomhole temperatures as used in the specification and claims is meanttemperatures in excess of about 250 F. which are commonly encountered inthe relatively deep wells of the order of more than l0,000 feet beingdrilled today. These particular substituted dihydroxybenzenes not onlyexhibit superior high-temperature stability but also maintain thedrilling fluid in the fluidized, low-gel state at such temperatures.

In addition the substituted dihydroxybenzene compounds of the presentinvention can be used as drilling fluid dispersants at much lowerconcentrations than known dispersants such as the calciumlignosulfonates or ferrochrome lignosulfonates in both highandlow-temperature applications in aqueous drilling fluids, particularly indrilling fluids suited for drilling operations in areas wherein heavingor slougjiing shale formations are encountered.

Another aspect of this invention is that a modified shale controldrilling fluid can be formulated for use in such heaving or sloughingshale fon'nations in a rapid, efficient manner especially with the4-methyl-, 4 (2'-carboxyethenyl)-, 4- methyl-5-chloro-, 4-nitro-,4-chloro, and 4-hydroxyl ,2- dihydroxybenzene species of the presentinvention. This modified shale control drilling fluid contains lime andcaustic but is free from any added water-soluble calcium salt. Thismodified shale control drilling fluid can attain the same beneficialresults as achieved with the shale control drilling fluid of Weiss andHall, US. Pat. No. 2,802,783, i.e., stabilizing and hardening the shaleformations in contact therewith.

The shale control drilling fluid of US. Pat. No. 2,802,783 requires awater-soluble calcium salt to be present therein to provide a calciumion concentration of 200 ppm. or more in the drilling fluid to attaincomparable shale hardening and stabilization.

This surprising and wholly unexpected result achieved with the 4-methyl,4-(2'-carboxyethenyl)-, 4-methyl-5-chloro, 4- nitro-, 4-chloro-, and4-hydroxy-l,2-dihydroxybenzene species of the present invention cannotbe attained with other known drilling fluid dispersants such as calciumlignosulfonate or ferrochrome lignosulfonate.

In the preparation of an improved drilling fluid in accordance with thisinvention a drilling fluid additive material can conveniently beemployed. in accordance with one embodiment, for use in drilling throughheaving or sloughing shale formations with a modified shale controlreagent additive admixture, a drilling fluid additive compositioncomprises an admixture of a water-soluble alkalinity agent such as limeor calcium hydroxide and the preferred substituted dihydroxybenaenecompounds of the present invention. The composition of this admixture isusually in the weight ratio range of 0.5 to 3.0 parts of the alkalinityagent lime or calcium hydroxide per part of the dihydroxybenzenecompound, preferably a weight ratio of 0.75 to 1.5 for the mostsatisfactory results. This modified shale control additive compositionembodiment is particularly suitable in drilling fluids being used inheaving or sloughing shale formations because it avoids the need ofusing therewith the water-soluble hygroscopic salt calcium chloride.

in another embodiment for a shale control additive composition such asdisclosed in U.S. Pat. No. 2,802,783, one may incorporate in the aqueousdrilling fluid a water-soluble calcium salt such as calcium chloride,calcium sulfate or the like in addition to lime and the substituteddihydroxybenzene compound, the weight ratio range of such an admixturemay be 0.5 to 3.0 parts of lime or calcium hydroxide alkalinity agent,0.l| .0 part of water soluble calcium salt, e.g., calcium chloride, and0.5 to 5 parts of substituted dihydroxybenzene compound. The aboveweight ratio ranges can be modified dependent on the equivalent ormolecular weights of the respective components of the admixture andwhether the components are employed in the anhydrous or hydrated form.

If desired other drilling fluid additives can be incorporated in theadditive composition such as starch or carboxymethyicellulose as waterloss agents, etc.

These additive admixtures are preferably in solid form but may also bein the form of an aqueous slurry or solution.

A drilling fluid in accordance with the present invention can beprepared by the addition of the drilling fluid reagent admixture towater or to a water-containing hydratable clayey material together withconventional drilling fluid materials such as water-loss agents,weighting agents, emulsifying agents and the like. One may also convertan aqueous drilling fluid such as a low-lime mud, a gyp mud, a shalecontrol mud, a high-pH low-lime mud, a sea water mud or the like to theaqueous drilling fluid of the present invention by the addition theretoof the additive composition disclosed herein or by the separate additionof the various components making up the admixture as required to providethe desired type drilling fluid containing the substituteddihydroxybenzene of the present invention.

The substituted dihydroxybenzenes of the present invention may be addedto an aqueous drilling fluid in amounts ranging from about 0.1 pound toabout l0 pounds per barrel of drilling fluid. In general, it has beenfound that amounts less than 0.I pound per barrel do not producecompletely satisfactory results in terms of dispersing activity whereasamounts above about pounds per barrel are economically unattractive andno improved results are obtained therewith. A preferred range for thesubstituted dihydroxybenzenes of the present invention is from about0.25 to about 5 pounds per barrel of drilling fluid for most consistentresults and efficiency.

The substituted dihydroxybenzenes employed in the present invention areknown compounds and the manner of their preparation is known in the art.

A general discussion of hightemperature phenomena follows, withparticular reference to the significance of shear or gel strengthmeasurements, and the viscosity of samples.

In general, some degree of high-temperature gelation occurs in mostclay-water systems when exposed to temperatures above normal. Hightemperatures affect the drilling fluids used in drilling operations torecover petroleum from underground formation. Under static conditionstemperature tends to accelerate the development of gel structure in themud. The end result of this gel development will depend upon thetemperature, time for development, and susceptibility of the mud togelation. The strength of the gel developed will range from a low,easily measured gel, through plasticity to a rigid cementlike mass whichpractically defies classification as a gel.

Another observed high-temperature effect is on viscosity. As with thegel development, temperature may have little or no effect on theviscosity of the mud or may thicken the mud to a point where it becomespractically unpumpable. The end viscosity of a mud appears to beindependent of whether the mud has been continually agitated or remainedquiescent during the heating cycle. The effect of temperature on thephysical properties of muds may be classified into three charac teristicpatterns.

NORMAL RESPONSE TO TEMPERATURE Drilling mud slurries possess a propertyknown as thix otropy. The clay particles of the slurry tend to orientthemselves with time under a static condition to produce a semirigid gelstructure. Elevated temperatures tend to accelerate the rate offormation and degree of development of this property to such an extentthat muds often develop gel structures of appreciable strength.

Muds possessing a normal response to temperature will refluidize to acondition approximating their original viscosity when subjected tomechanical agitation.

ABNORMAL RESPONSE TO TEMPERATURE In a second response to temperature,which is called hightemperature gelation, the muds undergo gelation toyield similar semirigid structures; but these gels are not thixotropic.Therefore, the muds will not refluidize satisfactorily but remain ashighly viscous to semiplastic slurries.

The degree of gelation cannot of itself be used to distinguish muds ofthis type for, although the degree of gelation in muds of this type isusually somewhat higher than in muds possessing normal temperatureresponse, there can be appreciable overlap between the two types. Theimportant criterion is the retention or loss of thixotropic responsefollowing hightemperature aging.

HIGH TEMPERATURE S/OLlDlFlCATlON The most severe reaction to temperatureis often referred to as high temperature solidification. In this case amore complex rigid structure is formed which in severe cases approachesa cementlike solid consistency. These muds usually have lost anyresemblance to a thixotropic fluid and upon agitation may tend togranulate and crumble into a discontinuous mass.

In the tables, gel strength (Gels) is reported as determined by ashearometer in accordance with the procedure in the American PetroleumInstitute publication RP-29, results being expressed either as pounds!I00 square feet or as time in seconds for a tube to settle in the mud(after the mud has stood for zero time and for ID minutes). If itsettles in more than 60 seconds, shear is reported as pounds per hundredsquare feet. Yield Point (YP) is calculated by subtracting the PlasticViscosity (PV) from the Fann Viscosity reading at 300 rpm. PlasticViscosity (PV) is obtained by calculation, subtracting the Fann readingat 300 rpm. from the 600 rpm.

TABLE I Shearometer M h gels, 1b.] Amount Ap. vis- 10011.1 AI!Additional and type eoslty, l'm, W.L. Pl, 1 u, 'ilnw. lrx. H additive,lbs. Type mud dispersant P\ ope. l pH 1-0. or. t'l. p p.111 hours ...L n0.5M 9 a 11.5 0.3 I211 12 2 13 9.5 J 3 16 In. l Nob] A 13 0 32 13 2 48 9.ltl Z 11. .15 9 2 4 hi 0 .i .1 0,211 1 iii High temp. shear 80 1Lpi1=Low pH mud. 1 A=2'-carb0Xyethenyi-1,2-dihydroxybenlene. 3ModSC=Modifled shale control mud (no CaCh or NaOH present).

TABLE II Shearometor gels, lbJ Amount Ap. vis 100 it! API Additional andtype cosity, Pm, W.L. Pl, Ca, Tlnlt Ex. additive, lbs. Typo muddispersant PV Y1 cpe. [l 10 i pH cc. cc. cc. ppm. hours 2 LpH 0.5 B 2 111| 15 u 18 4 16 L 1 1 V 1.0 B 10 11 -25 16 10 2 23 10 16 1.5 11 13 7 215 7 15 1.511 1:1 29 1.5 B 18 4 1.5 B 10 5 16 Properties niter bombing 8hrs. at 300 F. high temperature shear 280 2! 3.0 lime plus Sc 1 3.5 B 1111 14.5 3. a 4.1 12.1 12. 0 m 5. 2 2,1 16

1.0 CaClz.

Properties after bombing 8 hrs. at. 300 F. high temperature shear 200 1LpH=Low pH mod. 1 B =4ctsrb0Xy-1,2-dihydroxybenzene. I ModSC=Modifledshale control mud. l SC Shnle control mud.

TABLE III Shearometer Amount Additional and type 'Iirno Ex. additive,lbs. Type mud dispersant PV Y1 hours 3 LpH 05 C 16 13 2 Ill 4 16 10N8C13 32 3b..... 2 slime ModSG- 2 5 C 11 7 1 ii 0.25

4 1 LpII 0 26 D 4 13 3 2 2 16 4a 1. I41 I) 5 D l? 3 1B 7 D. 25

4b 14111 1 o D q 10 2 16 5 16 4e 2.5 lime M01180 2.5 I) 11 5 16 I-Lightemperature shear 80 1 LpH=Low pH mud.

1 C =Hormyl-LZ-dlhydmxybenzone.

l ModSC =Modified shale control mud. I D =4-chloro-l,Z-dihydroxybenzeno.

reading. Apparent Viscosity (AV) is equal to one half of the FannViscosity reading obtained at 600 r.p.m. The fluidity of a 6 5 mud canbe back calculated from these data, the results being expressed in FannViscosity at 600 rpm. and 300 r.p.m. for a direct reading viscosimetcr.

The properties of the base muds are shown in the tables.

The test data set forth in the following tables indicate the surprisingadvantages of the substituted dihydroxybcnzenes oi the present inventionand demonstrate the beneficial results of same in improving thedispersibility of drilling fluids.

Representative physical properties of drilling fluids both bestitutcddihydroxybenzenes of the present invention are shown in the tables. ineach example thereof the amount of material or materials added to thebase muds are shown, expressed in terms of pounds of material per barrelof drilling fluid.

The data in table 1 above show that 4-(2'-carboxyethenyl)-l,2-dihydroxybenzene is an effective dispersant in low pH and modifiedshale control drilling fluids. The data also show (examples lb and c)that the presence of considerable amounts of contaminants such as sodiumchloride do not adversely effect the properties of the drilling fluid.The data further show that material is most effective at concentrationsof 2 and 2.5

fore and after addition of various materials including the subpounds perbarrel after a time lapse of about it: hours, when used in a modifiedshale control mud and about 0.5 pound per barrel when used in a low-pHmud.

The data in table [I above show that 4-carboxyl ,2- dihydroxybenzene isan effective dispersant in aqueous drilling fluids after a period ofabout 2 hours, and that the best results are obtained after the materialis in the drilling fluid for a l6-hour period.

The data in the above table lll show that the 4-formyland the4-chloro-l,Z-dihydroxybenzene species are effective drilling-fluiddispersants in both low-pH and modified shale control mud systems.

1 ty of the mud at high temperatures.

Table VI above shows that 4-isopropyl-l,2-dihydrox- TABLE IV Shearometergels, lb. Amount Ap. vis- 100 it. API Additional and type cosity. Pm,W.L., Pl, Ca, Time. Ex. additive, lbs. Type mud dispersant PV YP ope. l01 pH cc. cc. cc. ppm. hours 9 6 12 LpH 0.6 E 13 8 17 14 10 19 5a r2.0NaCl r 0.515 1 5l).... 2.5 limo ModSC 3 2.5 E 13 2 t t Propertiesafter bombing 8 hours at 300 F. high temperature shear 80 1 LpH=Low pHmud. I E =4-nltrol ,2-dlhydroxybenzene. I M0dSC=M0dlfled shale controlmud.

TABLE V Shearometer gels, lb.l Amount AI). Vls- 100 l't. APl Additionaland type t'osity, Pm, W.Ii., Pl, Ca, Time, Ex. additive, lbs. Type muddispersant 1\' Y ope. 0 10 p11 cc. cc. cc. ppm hours 9 16. 5 t 9. 3 t t0. 25

6 Lpll 0.6F ll 2 12 9.5 r r 2 15 2 l6 0' (l 9.4 t 16.6 r 16 14 1 14. 5(l 0 9. 6 s r r 32 13 0 13 r t 9. 6 t t t t r t 0. 25

34 5 36.5 (1 0 9.9 r A. 15.8 t 16 20 5 22. 5 (1 0 l). B t r 32 10 i0 15r ll. 7 r i 0.

7t 2.5llme ModSG 10 8 14 4.3 4.6 12.1 3 8 64.8 10 16 High temperatureshear l LpH=Low pH mud.

1 F =1,2,4-trihydroxybenzene.

I G t-t-butyl-l.2-dlhydroxybenzene.

1 ModSC =M0dlfled shale control mud.

TABLE VI Amount Additional and type Ex. additive, lbs. Type muddispersant 1W Y! 9 16 a Lpil 0.25m {16 s 20 7 l2 5 20 6 22 4 l3 14 {20 025 0 'LpH =Low pH mud. 1 ii l-lsopropyH ,2dlhydroxybenzeno.

From the data in table lV it is evident that 4-nitro-l.2-

ybenzene is an effective drilling fluid dispersant at concentradihydruxyhenvene exhibits satisfactory ispersing activity in a 7g tionsof 0.252.0 pounds per barrel. The low Yield Point and low-pH mild andalso in a modified shale control mud. The low Yield Point values andzero gels obtained with this material in a modified shale control mud atconcentrations of about 2.5 pounds per barrel are indicative of thedispersing activity of this material.

Gel Strength Values shown in the table demonstrate its effectiveness ina low-pH mud system. Example 8b shows that the presence of moderateamounts of salt as a contaminant does not adversely effect the desirablecharacteristics imparted to 7 5 the drilling fluid by this material.

TABLE IX ('t1n li |u| i Shearometer go Amount Ap. vis- 100 ft. AP!

Additional and type cosity, Pm, W.L., Pi. Ca, Time, Ex. additive, lbs.Type mud dispersant PV YP ope. pH cc. cc. cc. ppm. hours ll 196 109 .H24

i3 3.0 lime plus 1.0

lb 58 44 0. 26 CaCh. SC 3.5 KEM 19 i7 27. 5 31 7 34.5 122 104 3L2 16 62416 Properties alter bombing for 8 hours at 300 F. high temperature shear600 ModSC =M0d1fled shale control mud. I I =-4-methyI-L2mhydroxybenzene.

1 S0 Shale control mud. %-B =Q bro|:in. I E M Calciurn lignosullonste.

TABLE X Shearometer Amount Additional and type Ex. additive. lbs. Typemud dispersant PV YI 14 2.5lime. LpH 2.01 13 11 Z) 3.0lime ModSC 1.51 111 10 3 Properties alter bombing 8 hours at 300 F. high temperature shear80 7 0 8 l9 l6 2.5 lime 1.751 10 l 10 3 Properties aiter bombing 8 hoursat 300 F. high temperature shear fil I LpH -Low pH mud. 1 l-l-methl-lJdihydroxybensene. l ModSC: odiilad shale control mud.

TABLE XI Bhearometer gels, lb. Amount Ap. vls- 10D it.= API Additionaland type coslty, Pm, W.L., Pi, Ca, Time, Ex. additive. lbs. Type muddispersant PV 1? cps. 0 10 pH cc. cc. cc. p.p.m. hours LpH 1.5 W 19 24LpH 4.010 9 24 24 LpH 0.5 Y 18 16 1.0 Y 10 32 i6 ModSC- 2.5 Y 7 84 16 1%lvpli=Low pH mad. I 1,2,Hrilg2roxybensonc.

The above table lX shows the properties of modified shale Kembrqek,respectively. examples [2 and 13, showed advfiim control drilling fluidscontaining 4-methyl-l,2-dihydrox- P P the 3 h ur! 300 F. treatm n The filybenzene. temperature shear value obtained with example ll 80) 18 morethan 400 percent less than the 390 value obtained with l p examplecomaining example [2 containing Q-Broxin and at least 750 percent lessmerc'al impel-Sam P and example comammg a than the 600 value obtained inexample 13 containing Kemcium lignosulfonate dispersant sold by thetrade name Kernbreak.

break" were included in the table. These commercial disper- Table xabove shows that 4 methyl l2 dihydmxybenzene sams '9 made up a shalecomm mud i y! also exhibits excellent dispersing properties in low-pHand l needed shale comm chcimstry m a dnlhng modified shale control mudsystems at varying concentrations fluid without having a source ofsoluble calcium salt present. and hat these Properties are retained anthe muds have The mud properti s f x mpl I 1. shown in h l inbeen heatedfor 8 hours at 300 F. In examples 15-17 the highdicate the 4-methyl-l,Z-dihydroxybenzene is superior to temperature shear values were lessthan 80, the lowest reading either of those commercial dispersants,particularly with obtainable on the test instrument.

respect to the very low Yield Point values obtained therewith, The datain table XI shows that other substituted comaiter IS minutes, 2 hoursand 16 hours. Particularly significant pounds such as1,2,3-trihydroxybenzene, l,3-dihydroxis the retention of desirabledrilling fluid properties after expoybenzene and 4-hydroxycinnamic aciddo not exhibit sure to a temperature of 300 F. for 8 hours as is shownfor exdispersing activity in aqueous drilling fluids as is evidenced byample l 1 whereas the drilling fluids containing Q-Broxin and thehigh-gel values obtained therewith.

TABLE XII Shearometer gels, lb./ Amount Ap. vis- 100 it! API Additionaland type c ty, Pm, W.L., P1, Ca, Time- Ex. additive. lbs. Type muddispersant PV YP ope. pH cc. cc. cc. p.p.m. hours 18 1 0. 2t! 21 LpH0.36 J H 7 2 2o 6 l6 l1 6 0. m 22 LpH 0.5 K 3 2 l9 6 l6 9 0 0. 22s 2.0 K11 1 2 l4 1 16 23 LpH 2.0 L 19 7 16 l LpH=Low pH mud. IJ=4-methy1-5-chloro-l.24ilhydroxybenzene. iK=2,5-dihydrory-L4-benzoquinone. I L 2,6dihydroxy-3,6-dichloro-1,4-benzoquinone.

TABLE XIII Bhearomoter ge Amount .Ap. visl ft. APl Additions] and typecoslty, Pm, W.L., Pi, Ca, Time. Ex. additive, lbs. Type mud dispersantPV YP cpe. 0 10 pH cc. cc. cc. p.p.m hours 24 LpH 0.5 WW 16 24a 2.0ww 1624b 2.5 WW it? 25 LpH 0.5 XX 6 25a 4 1.0 XX g: 0. 25 26 LpH 0.5 YY 0. 25an 2.0 YY 2 10 l LBVH= Low pH mud. 9 W =tetrahydrox -1,4-benwquinone.ModBC=Modlfi shale control mud. 4 XX=Di Potassium Rhodimnste. Y Y2,3,4-trlhydroxy-l-decanoylbenzene.

TABLE XIV Shearometer 8 1 Amount Ap. vls- I00 it A?! Additional and typecoslty, Pm, W.L., Pl, On, Time, Ex. additive, lbs. Type mud dispersantPV YP cpe. 01 10 pH cc. co. or. ppm. hours 13 0. 25 27 L H 0.35 M {11 1927a 2.5 lh'ne ModSC 2.5 M 0 32 Properties after bombing 8 hours at 300F. high temperature sheer 80 l l PH =Low pH mud. 2 =ll0/50 RE weightmixture of t-methyl-li ehlorol,Z-dihydroxybenzene andi-msthyld,2-dihydroxybemenev 1 ModSC= odlfled shale control mud.

The data in table Xll above show that 4-methyl-5-chloroi,2-dihydroxybenzene, 2,5-dihydroxyl ,4-benzoquinone and2,5-dihydroxy-3,6-dichloro-l,4-benzoquinone are effective drilling fluiddispersants (examples 21-23 inclusive).

The data in table Xlll above show that other substituted benzenecompounds such as tetrahydroxy-l,4-benzoquinone, dipotassium rhodizonateand 2,3,4-trihydroxy-l-decanoylbenzene are inefi'ective drilling fluiddispersants.

Table XIV above shows that mixtures of the substituted dihydroxybenzenesof the present invention are effective dispersants in aqueous drillingfluids and that these mixtures also exhibit good high-temperatureproperties.

The substituted dihydroxybenzene compounds of the present invention canbe used in the form of mixtures in drilling fluids. Suitable ranges arefrom -70 percent of one dihydroxybenzene compound and 70-30 percent ofanother dihydroxybenzene compound. A particularly desirable range is inthe order of about 40-60 percent of one compound and -40 percent of theother compound.

Obviously, many modifications and variations of the invention ashereinbefore set forth may be made without departing from the spirit andscope thereof, and therefore, only such limitations should be imposed asare indicated in the appended claims.

lclaim:

I. An aqueous drilling fluid containing clay solids dispersed thereinand as the dispersant a substituted dihydroxybenzene compound selectedfrom the group consisting of 2,5-dihydroxyl ,d-benzoquinone,2,5-dihydroxy-3,6-dichlorol ,4- benzoquinone, 4,5-dihydroxy-l.Lbenwquinone, 4,5 dihydroxy-S,6-dichloro-l,Z-benzoquinone and mixturesof said compounds, said dihydroxybenzene compound being present in thedrilling fluid in an amount sufficient to reduce the viscosity thereof.

2. An aqueous drilling fluid as claimed in claim I wherein thesubstituted dihydroxybenzene compound is 2,5-dihydroxyl ,4-benzoquinone.

3. An aqueous drilling fluid as claimed in claim I wherein thesubstituted dihydroxybenune compound is 2,5dihydroxy-3,6-dichloro l ,4-benzoquinone.

4. An aqueous drilling fluid as claimed in claim 1 wherein thesubstituted dihydroxybenzene compound is 4,5-dihydroxyl ,2-benzoquinone.

5. An aqueous drilling fluid as claimed in claim I wherein thesubstituted dihydroxybenzene compound is 4,5-dihydroxy-3,6-dichlorol.Z-benzoquinone.

6. An aqueous drilling fluid as claimed in claim I wherein 75 thesubstituted dihydroxybenzene compound is present in the drilling fluidin an amount of from about 0.1 to l pounds per barrel ofdrilling fluid.

7. An aqueous drilling fluid according to claim I wherein thesubstituted dihydroxybenzene compound is present in the drilling fluidin an amount of from about 0.25 to pounds per barrel of drilling fluid.

8. A method of drilling wells wherein a drilling fluid is passed throughthe well in contact with earth formations during the drilling operation,the improvement which comprises contacting said earth formations with anaqueous drilling fluid containing clay solids dispersed therein and asthe dispersant at least 0.1 pound per barrel of drilling fluid of asubstituted dihydroxybenzene compound selected from the group consistingof 2,5-dihydroxy-l,4-benzoquinone, 2,5-dihydroxy-3,6- dichloro- 1,Lbenzoquinone, 4,5-dihydroxy-l ,2-benzoquinone,4,5-dihydroxy-3,6-dichlorol .Z-benzoquinone and mixtures of saidcompounds, said substituted dihydroxybenzene compound being present inthe drilling fluid in an amount sufficient to reduce the viscositythereof.

9. A method as claimed in claim 8 wherein the substituteddihydrosybenzene compound benzoquinone.

[0. A method as claimed in claim 8 wherein the substituteddihydroxybenzene compound is 2,5-dihydrosy-3.6-dichlorolA-benzoquinone.

II. A method as claimed in claim I wherein the substituteddihydroxybenzene compound is 4.5-dihydroxyl ,2- benzoquinone.

12. A method as claimed in claim 8 wherein the substituteddihydroxybenzene compound is 4,54iihydroxy-3 ,6-dichloro-1,2-benzoquinone.

13. An aqueous drilling fluid as claimed in claim I wherein thesubstituted dihydroxybenaene compound is present in the drilling fluidin an amount of from about 0.1 to [0 pounds per barrel of drillingfluid.

14. An aqueous drilling fluid according to claim 8 wherein thesubstituted dihydroxybenune compound is present in the drilling fluid inan amount of from about 0.25 to 5 pounds per barrel of drilling fluid.

is 2.5-dihydroxyl ,4-

Egg? 1 UNITED STATES PA ENT OFFICE QERTIFIQATE 0F CUREUTWN Patent 3 37H9January 25, 1972 Dated Inventor(s) Jack H. a-n

It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

T'Table Iv, Ex. 5a Under 1gp. viscosity, cpe, "l6 5" should w Table IX,Ex. 11 Under Time, Igours, "0.25, 6, 12" should be Table X, Ex. 6 UnderPf, coo should be --O.8--

Table XI, Ex. 20a Under pH "0.6 should be --9.6--

Table XII, Ex. 23 Under Shearometer gels, "5.2" should be Table XIII,Ex. 2 th Under Ap. viscosity "l5 5" should be Signed and sealed this 5thday of December 1972.

(SEAL) Attest:

EDWARD M.FLETCHER, JR 7 ROBERT GOTTSCHALK Attesting Officer Commissionerof Patents zg ga UNITED STATES PATENT OFFICE I I CERTIFICATE OFCORRECTION patent 3, 37,492 Dated January 25, 1972 Inventor) Jack H.Kolaian It is certified that error appears in the above-identifiedpatent and thatsaid Letters Patent are hereby corrected as shown below:

F'I'able Iv, Ex. 5a Under Ap. viscosity, ope, "l6 5" should be -l6.5-Table IX, Ex. 11 Under Time, gours, "0.25, 6, 12" should be +0.25 2, 1 ITable x, Ex. 6 Under fir, cc., should be --o.8-- Table XI, Ex. 20a.Under pH "0.6 should be --9.6--

Table XII, Ex. 23 Under Shearometer gels, "5.2" should be 2 ".5, TableXIII, Ex. 2 +b Under. Ap, viscosity 15 5" should be Signed and sealedthis 5th day of December 1972.

(SEAL) Attest:

EDWARD M.FLETCI-IER,JR.U I ROBERT GOTTSCHALK .Attesting OfficerCommissioner of Patents 3 3 V UNITED STATES PATENT OFFICE CERTIFICATE OFCORRECTION patent 3, 37, 9 Dated January 25, 1972 Inventor(s) Jack Klaian It is certified that error appears in the above-identified patentand that said Letters Patent are hereby corrected as shown below:

[Table Iv, Ex. 5a. Under 1gp. viscosity, ope, "l6 5" should Table IX,Ex. 11 Under Time, IIours, "0.25, 6, 12" should be Teble X, Ex. 6 UnderPf, cc. should be --O.8-

Table XI, Ex. 20a. Under pH "0.6 should be -9.6-

Table XII, Ex. 23 Under Sheerometer gels, "5.2" should be Table XIII,Ex. 2 lb Under Ap. viscosity "l5 5" should be Signed and sealed this 5thday of December 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,J'R. ROBERT GOT'ISCHALK Attesting OfficerCommissionerof Patents

2. An aqueous drilling fluid as claimed in claim 1 wherein thesubstituted dihydroxybenzene compound is 2,5-dihydroxy-1,4-benzoquinone.3. An aqueous drilling fluid as claimed in claim 1 wherein thesubstituted dihydroxybenzene compound is2,5-dihydroxy-3,6-dichloro-1,4-benzoquinone.
 4. An aqueous drillingfluid as claimed in claim 1 wherein the substituted dihydroxybenzenecompound is 4,5-dihydroxy-1,2-benzoquinone.
 5. An aqueous drilLing fluidas claimed in claim 1 wherein the substituted dihydroxybenzene compoundis 4,5-dihydroxy-3,6-dichloro-1,2-benzoquinone.
 6. An aqueous drillingfluid as claimed in claim 1 wherein the substituted dihydroxybenzenecompound is present in the drilling fluid in an amount of from about 0.1to 10 pounds per barrel of drilling fluid.
 7. An aqueous drilling fluidaccording to claim 1 wherein the substituted dihydroxybenzene compoundis present in the drilling fluid in an amount of from about 0.25 to 5pounds per barrel of drilling fluid.
 8. A method of drilling wellswherein a drilling fluid is passed through the well in contact withearth formations during the drilling operation, the improvement whichcomprises contacting said earth formations with an aqueous drillingfluid containing clay solids dispersed therein and as the dispersant atleast 0.1 pound per barrel of drilling fluid of a substituteddihydroxybenzene compound selected from the group consisting of2,5-dihydroxy-1,4-benzoquinone,2,5-dihydroxy-3,6-dichloro-1,4-benzoquinone,4,5-dihydroxy-1,2-benzoquinone,4,5-dihydroxy-3,6-dichloro-1,2-benzoquinone and mixtures of saidcompounds, said substituted dihydroxybenzene compound being present inthe drilling fluid in an amount sufficient to reduce the viscositythereof.
 9. A method as claimed in claim 8 wherein the substituteddihydroxybenzene compound is 2,5-dihydroxy-1,4-benzoquinone.
 10. Amethod as claimed in claim 8 wherein the substituted dihydroxybenzenecompound is 2,5-dihydroxy-3,6-dichloro-1,4-benzoquinone.
 11. A method asclaimed in claim 8 wherein the substituted dihydroxybenzene compound is4,5-dihydroxy-1,2-benzoquinone.
 12. A method as claimed in claim 8wherein the substituted dihydroxybenzene compound is4,5-dihydroxy-3,6-dichloro-1,2-benzoquinone.
 13. An aqueous drillingfluid as claimed in claim 8 wherein the substituted dihydroxybenzenecompound is present in the drilling fluid in an amount of from about 0.1to 10 pounds per barrel of drilling fluid.
 14. An aqueous drilling fluidaccording to claim 8 wherein the substituted dihydroxybenzene compoundis present in the drilling fluid in an amount of from about 0.25 to 5pounds per barrel of drilling fluid.